Is there an alternate planet with other humans? But they probably evolved differently. They'd speak a different language. What if 'aliens' are other 'humans'? WHAT IF WE ARE THE ALIENS?

To any other planet we would be considered the "aliens" because we are from somewhere different. I lay awake at night thinking about how somewhere else in the galaxy there could be a planet with creatures you can't even possibly describe or imagine. I personally think we are not alone. I mean, the Galaxy never ends, how can we be the only ones out there? Haha

Here is one definition of alien:  A creature that comes from somewhere other than the planet Earth.

I assume anyone living on another planet would simply have their own definition of alien.

CS Lewis wrote a book called Perelandra. Here's a description of the book on the goodreads site:  "The second novel in Lewis's science fiction trilogy tells of Dr Ransom's voyage to the planet of Perelandra (Venus). Dr Ransom is sent by the Elida to Perelandra (Venus) to battle against evil incarnate and preserve a second Eden from the evil forces present in the possessed body of his enemy, Weston. Through these works, Lewis explores issues of good and evil, and his remarkable and vividly imaginative descriptions of other worlds cements his place as a first-class author of science fiction adventure."

Notice that it refers to a "second Eden" not a "second human race."

My point is that it can give you a fascinating perspective of what may exist beyond the "orbit of the moon."

Lewis considered it his greatest work.  I agree.

To another race we would be aliens, Now whether they are sentient enough to understand that is an interesting assertion.

While there is most likely other life forms, we would have no idea at what stage these life forms could be . . . . Even to consider them humanoid is quite the stretch . . . But you never know.